Trained Neuromechanical Adaptations Associated with ACL Injury Prevention Programs.

Abstract

Anterior cruciate ligament (ACL) injury is the largest single problem in orthopedic sports medicine. Injury prevention protocols have been developed to target the reduction of ACL injury risk during dynamic landings. The current prevention programs are purported to promote successful neuromechanical modifications through adaptation of both lower limb neuromuscular control strategies and joint biomechanics. In spite of these ongoing efforts, however, ACL injury rates and their associated sex disparity have endured. The intent of this dissertation was to assess and potentially improve the effectiveness of the current injury prevention model. Aim one assessed the relations between neuromuscular control strategies and knee joint biomechanics during unilateral landings. Increased quadriceps activation was found to coincide with greater sagittal plane knee kinetics during unilateral jump landings. Aim two compared lower limb joint biomechanical adaptations between unilateral and bilateral landings following a standard neuromuscular training program. It was demonstrated that trained adaptations were only evident during bilateral landings, and unilateral and bilateral landings presented substantially different lower limb biomechanical profiles. Aim three examined the extent to which core stability and plyometric components, used as single modalities, can modify “high- risk” landing biomechanics, as compared to standard neuromuscular and no training models. Plyometric exercises, used in isolation, have the ability to modify hip and knee biomechanics, but only during bilateral landings. The standard neuromuscular training model, however, displayed the potential to promote biomechanical adaptations during unilateral landings. It may be to promote lower limb biomechanical adaptations during unilateral landings future prevention modalities should combine two or more training components to maximize potential benefits. Finally, aim four examined the changes in neuromuscular control strategies that coincide with modifications in joint biomechanics elicited during unilateral landings following isolated core stability, plyometric, standard neuromuscular and no training programs. Core stability and plyometric training were found to produce trained modifications of quadriceps and hamstring activation patterns that predict changes of lower limb sagittal plane loading and frontal plane knee kinematics. It appears that inclusion of both core stability and balance, and plyometric exercises may be necessary to promote a “safer” knee neuromechanical profile.